Characterization of substrate doping and series resistance during solar cell efficiency measurement

Abstract

Short-circuit current, maximum power, and open circuit voltage during a single flash are determined by varying intensity, voltage, and current. An apparatus determines the substrate doping and the series resistance of the solar cell. The series resistance of the cell is determined from a voltage step from the maximum power voltage operating point to the open-circuit condition. Methods are described for determining the substrate doping from stepping or sweeping the voltage. The first uses a voltage step and finds the change in charge that results. This determines a unique doping if the series resistance is known. The second uses data for a case of varying current, voltage, and light intensity, and compares this data to the case of varying voltage and intensity with no current. By transposing both cases into the steady state, agreement between the two data sets is found for unique doping and series resistance values.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority of U.S. provisional patent application No. 61 / 822,058, filed May 10, 2013, entitled “Characterization Substrate Doping and Series Resistance During Solar Cell Efficiency Measurement,” which is hereby incorporated by reference.FIELD OF THE INVENTION[0002]The present invention relates generally to solar cell testing. More specifically, the present invention relates to measuring solar cell parameters, substrate doping and series resistance using a single flash pulse.BACKGROUND OF THE INVENTION[0003]Conventional solar-cell testers typically report a set of parameters related to the current-voltage (I-V) curve shape at one-sun light intensity in addition to the power output of the solar cell. Typically, these parameters include: short-circuit current density (Jsc), open-circuit voltage (Voc), Power (Pmp), and fill factor (FF). One method to measure these parameters is described in U.S. Pat. No. 7,696,461. In th...

AI Technical Summary

Benefits of technology

The present invention utilizes a single flash pulse to measure important parameters of a solar cell, such as the maximum power point voltage and substrate doping. This is done by measuring short-circuit current, maximum power point voltage, and current from a single flash pulse. The invention also includes methods for measuring doping and series resistance of the solar cell using a single flash pulse. The results from this invention are accurate, as they account for both the steady-state power and transient effects during the measurement. This allows for the use of data that can vary during the measurement, and the data can be corrected to correspond with the steady state results. Overall, this invention provides more efficient and accurate ways to measure important parameters of solar cells or modules.

Problems solved by technology

While this is the most important information for rating the output power and performance of the solar cell or module, it is not a complete device physics characterization of the device.

Images